// Copyright (C) 2024 Kumo inc.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//

#include <iostream>

#include <deneb/lru.h>

using Cache = deneb::Cache<int, int>;

int fibonacci(int n, Cache& cache) {
  if (n < 2) return 1;

  // We internally keep track of the last accessed key, meaning a
  // `contains(key)` + `lookup(key)` sequence will involve only a single hash
  // table lookup.
  if (cache.contains(n)) return cache[n];

  auto value = fibonacci(n - 1, cache) + fibonacci(n - 2, cache);

  // Caches are 100% move-aware and we have implemented
  // `unordered_map` style emplacement and insertion.
  cache.emplace(n, value);

  return value;
}

int fibonacci(int n) {
  // Use a capacity of 100 (after 100 insertions, the next insertion will evict
  // the least-recently accessed element). The default capacity is 128. Note
  // that for fibonacci, a capacity of 2 is sufficient (and ideal).
  Cache cache(100);
  return fibonacci(n, cache);
}

auto main() -> int {
  std::cout << fibonacci(32) << std::endl;
}
